Sex-Influenced Trait

and Epistatic Interaction

 

Only heterozygous polled cattle ever grow scurs (see red section in Table below), which is the epistatic interaction.  Two scurred alleles are required in females and only one in males, which is typical of a sex-influenced trait.

 

 

Genotype

Cows

Bulls

 

PP Sc/Sc

smooth polled

smooth polled

PP Sc/sc

smooth polled

smooth polled

PP sc/sc

smooth polled

smooth polled

Pp Sc/Sc

scurs

scurs

Pp Sc/sc

smooth polled

scurs

Pp sc/sc

smooth polled

smooth polled

pp Sc/Sc

horned

horned

pp Sc/sc

horned

horned

pp sc/sc

horned

horned

 

P = polled allele

P = horned allele

Sc = scurred allele

sc = allele for no scurs

 

 

 

Sheila Schmutz, PhD.   Jan. 31, 2007

See also http://homepage.usask.ca/~schmutz/polled.html